The formation of holes in poured or cast concrete structures can be achieved by a variety of available molding or forming dies or mandrels. These dies can range from rudimentary structures to complex assemblies.
A typical casting process in which one or more openings or holes are formed in a manhole involves positioning hole forms, e.g. a plug or mandrel, through a wall of the casting mold or between walls of a casting mold. Since the alignment of wall penetrations vary widely from one structure to the next and can require changes in elevation, penetration angle, diameter, etc., the number of hole form shapes is virtually infinite.
Current practice is to place a hole form through a cutout in the reinforcing steel structure and secure it in place using thin wire. This method does not position the hole form with sufficient accuracy, and the wire ends tend to scrape the hole form during casting and vibration, creating surface blemishes in the hole form which reduces its life and effectiveness.
An alternative method of mounting hole forms involves the use of vacuum generating devices that are permanently attached to hole forms. Such vacuum generating devices consist of multiple components which are easily degraded by dust and abrasion, limiting the durability and effectiveness of these devices. Also, being an attachment device, the expense of the vacuum holder must be included into the cost of each hole form, making the overall expense of the assembly unreasonably high.
The present invention provides a means and method for securing hole forms in place during casting operations.